1. Field of the Invention
This invention relates to tilting crucible furnaces. More specifically, a compact and highly efficient reverberatory furnace and recovery method are disclosed for direct smelting of a precious metal containing material into a dore button of precious metal.
2. Description of the Prior Art
It is well known in the art to provide crucible furnaces for smelting small batches of non-ferrous metals. In those devices, the charge is melted in a refractory or metal pot which may be fired either by external means or internally as by gas or oil burners, for example. In the past, small furnaces were typically fixed and the pot had to be removed for pouring. This removal increases the risk of mechanical and thermal damage to the pot. Larger tilting furnaces which have integral refractory pots are, however, known.
It is also known, that use of a reverberatory furnace, i.e., one in which the flame directly contacts the charge, is desirable in order to increase the oxidation of impurities in the charge.
In the smelting of silver, it is known that adding silicates to the charge can aid in providing easily fusible slag. Inclusion of soda-ash, fluorspar, and borax are also known to be beneficial in the production of a thoroughly liquid slag. Addition of nitre is known to be helpful in the partial oxidation of sulfides.
As mentioned above, the only known tilting furnaces are relatively large and would, therefore, not be economical for the recovery of small quantities of precious metal. There is, therefore, a need for a tilting reverberatory furnace of relatively small dimension which is efficient to use in the recovery of precious metals.